Plasticity gives plants the ability to adapt their morphology and growth to various environments. Environmental factors can lead to changes in the growth forms of algae. Halimeda opuntia was used as a model organism to determine the effects of highly irradiated and shade conditions in the field and its responses to low light conditions in the laboratory, which are known to be some of the main factors driving its morphological plasticity. To investigate the morphological and anatomical characteristics of the species, a total of 61 characteristics and 54 samples from Thailand, Japan and Indonesia were examined. In addition, we also tested the response under different light conditions in the laboratory. A phylogenetic tree was constructed using the tufA marker to confirm the species identification. We found that the thallus forms, branching patterns and segment shapes and sizes responded to the different light conditions. A brittle thallus network was found under shade conditions with low light intensity, while a compact thallus form was found under highly irradiated conditions. The H. opuntia segment shape was reniform under highly irradiated conditions, but its segments were adapted to be deeply trilobed in the lower thallus and tripartite shape in the upper thallus under shade conditions. The segment size also adapted; the segments in shaded areas were longer than those in sunny areas, which might have helped them increase their thallus height to ensure exposure to the high light habitat. This morphological variation and plasticity expanded our understanding of the range of H. opuntia plasticity present in the field and could help explain why this species is common and successfully colonizes various habitats worldwide.

中文翻译：

---

Halimeda opuntia (Bryopsidales, Chlorophyta) 对光照强度的表型可塑性和形态适应

可塑性使植物能够使它们的形态和生长适应各种环境。环境因素会导致藻类生长形式的变化。Halimeda opuntia 被用作模式生物，以确定野外高度辐照和阴凉条件的影响及其对实验室低光照条件的反应，这是驱动其形态可塑性的一些主要因素。为了研究该物种的形态和解剖特征，共检查了来自泰国、日本和印度尼西亚的 61 个特征和 54 个样本。此外，我们还在实验室测试了不同光照条件下的响应。使用tufA标记构建系统发育树以确认物种鉴定。我们发现叶状体形成，分支模式和节段的形状和大小对不同的光照条件做出反应。在低光强度的阴凉条件下发现了脆性的叶绿体网络，而在高辐照条件下发现了紧凑的叶绿体形式。仙人掌节段在强辐照条件下呈肾形，但在遮荫条件下，其节段在下部叶体中呈深三叶形，在上部叶体中呈三叶状。段大小也进行了调整；阴影区域的部分比阳光区域的部分长，这可能有助于它们增加叶状体高度，以确保暴露于强光栖息地。这种形态变异和可塑性扩大了我们对 H.